62 lines
1.6 KiB
Go
62 lines
1.6 KiB
Go
package patterns
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import "image"
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import "git.tebibyte.media/sashakoshka/tomo/canvas"
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// Texture is a pattern that tiles the content of a canvas both horizontally and
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// vertically.
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type Texture struct {
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canvas.Canvas
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}
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// Draw tiles the pattern's canvas within the given bounds. The minimum
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// points of the pattern's canvas and the destination canvas will be lined up.
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func (pattern Texture) Draw (destination canvas.Canvas, bounds image.Rectangle) {
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drawBounds := bounds.Canon().Intersect(destination.Bounds())
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if drawBounds.Empty() { return }
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dstData, dstStride := destination.Buffer()
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srcData, srcStride := pattern.Buffer()
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srcBounds := pattern.Bounds()
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dstPoint := image.Point { }
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srcPoint := drawBounds.Min.Sub(bounds.Min).Add(srcBounds.Min)
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srcPoint.X = wrap(srcPoint.X, srcBounds.Min.X, srcBounds.Max.X)
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srcPoint.Y = wrap(srcPoint.Y, srcBounds.Min.Y, srcBounds.Max.Y)
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for dstPoint.Y = drawBounds.Min.Y; dstPoint.Y < drawBounds.Max.Y; dstPoint.Y ++ {
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srcPoint.X = srcBounds.Min.X
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dstPoint.X = drawBounds.Min.X
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dstYComponent := dstPoint.Y * dstStride
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srcYComponent := srcPoint.Y * srcStride
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for {
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dstIndex := dstYComponent + dstPoint.X
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srcIndex := srcYComponent + srcPoint.X
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dstData[dstIndex] = srcData[srcIndex]
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srcPoint.X ++
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if srcPoint.X >= srcBounds.Max.X {
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srcPoint.X = srcBounds.Min.X
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}
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dstPoint.X ++
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if dstPoint.X >= drawBounds.Max.X {
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break
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}
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}
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srcPoint.Y ++
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if srcPoint.Y >= srcBounds.Max.Y {
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srcPoint.Y = srcBounds.Min.Y
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}
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}
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}
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func wrap (value, min, max int) int {
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difference := max - min
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value = (value - min) % difference
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if value < 0 { value += difference }
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return value + min
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}
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